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Quick facts
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 997010
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
Quinine sulfate capsule USP is a cinchona alkaloid indicated for treatment of uncomplicated Plasmodium falciparum malaria ( 1 ). Quinine sulfate capsule USP is an antimalarial drug indicated only for treatment of uncomplicated Plasmodium falciparum malaria. Quinine sulfate has been shown to be effective in geographical regions where resistance to chloroquine has been documented [see CLINICAL STUDIES ( 14 )] . Quinine sulfate capsules USP are not approved for: Treatment of severe or complicated P. falciparum malaria. Prevention of malaria. Treatment or prevention of nocturnal leg cramps [see WARNINGS AND PRECAUTIONS ( 5.1 )] .
About this medicine
Quinine sulfate is a cinchona alkaloid chemically described as cinchonan-9-ol, 6'-methoxy-, (8α, 9R)-, sulfate (2:1) (salt), dihydrate with a molecular formula of (C 20 H 24 N 2 O 2 ) 2 •H 2 SO 4 •2H 2 O and a molecular weight of 782.94. The structural formula of quinine sulfate is: Quinine sulfate occurs as a white, crystalline powder that darkens on exposure to light. It is odorless and has a persistent very bitter taste. It is only slightly soluble in water, alcohol, chloroform, and ether. Quinine sulfate capsules USP are supplied for oral administration as capsules containing 324 mg of the active ingredient quinine sulfate USP, equivalent to 269 mg free base. Inactive ingredients: black iron oxide, corn starch, gelatin, magnesium stearate, potassium hydroxide, propylene glycol shellac, sodium lauryl sulfate, and talc. 1
Who should not take it
Quinine sulfate is contraindicated in patients with the following: Prolongation of QT interval ( 4 ) Glucose-6-phosphate dehydrogenase (G6PD) deficiency ( 4 ) Myasthenia gravis ( 4 ) Known hypersensitivity to quinine, mefloquine, or quinidine ( 4 ) Optic neuritis ( 4 ) Quinine sulfate is contraindicated in patients with the following: • Prolonged QT interval. One case of a fatal ventricular arrhythmia was reported in an elderly patient with a prolonged QT interval at baseline, who received quinine sulfate intravenously for P. falciparum malaria [see WARNINGS AND PRECAUTIONS ( 5.3 )]. • Glucose-6-phosphate dehydrogenase (G6PD) deficiency. • Hemolysis can occur in patients with G6PD deficiency receiving quinine. • Known hypersensitivity reactions to quinine. • These include, but are not limited to, the following [see WARNINGS AND PRECAUTIONS ( 5.6 )] : • Thrombocytopenia • Idiopathic thrombocytopenia purpura (ITP) and Thrombotic thrombocytopenic purpura (TTP) • Hemolytic uremic syndrome (HUS) • Blackwater fever (acute intravascular hemolysis, hemoglobinuria, and hemoglobinemia) • Known hypersensitivity to mefloquine or quinidine: cross-sensitivity to quinine has been documented [see WARNINGS AND PRECAUTIONS ( 5.6 )]. • Myasthenia gravis. Quinine has neuromuscular blocking activity, and may exacerbate muscle weakness. • Optic neuritis. Quinine may exacerbate active optic neuritis [see ADVERSE REACTIONS ( 6 )] .
Warnings and cautions
Not indicated for the prevention or treatment of nocturnal leg cramps. Risk of serious and life-threatening adverse reactions ( 1 , 5.1 ). Thrombocytopenia, including ITP and HUS/TTP, has been reported. Discontinue drug ( 5.2 ). QT prolongation and ventricular arrhythmias. Avoid concomitant use with drugs known to prolong QT interval ( 5.3 ). Avoid concomitant use with rifampin. Quinine sulfate treatment failures have been reported ( 5.4 ). Avoid concomitant use with neuromuscular blocking agents. Quinine sulfate may potentiate neuromuscular blockade and cause respiratory depression ( 5.5 ). Serious and life threatening hypersensitivity reactions. Discontinue drug ( 4 , 5.6 ). Atrial fibrillation and flutter. Paradoxical increase in ventricular rate may occur. Closely monitor digoxin levels if used concomitantly ( 5.7 ). Hypoglycemia. Monitor for signs and symptoms ( 5.8 ). 5.1 Use of Quinine Sulfate for Treatment or Prevention of Nocturnal Leg Cramps Quinine sulfate may cause unpredictable serious and life-threatening hematologic reactions including thrombocytopenia and hemolytic-uremic syndrome/thrombotic thrombocytopenic purpura (HUS/TTP) in addition to hypersensitivity reactions, QT prolongation, serious cardiac arrhythmias including torsades de pointes, and other serious adverse events requiring medical intervention and hospitalization. Chronic renal impairment associated with the development of TTP, and fatalities have also been reported. The risk associated with the use of quinine sulfate in the absence of evidence of its effectiveness for treatment or prevention of nocturnal leg cramps, outweighs any potential benefit in treating and/or preventing this benign, self-limiting condition [see BOXED WARNING and CONTRAINDICATIONS ( 4 )] . 5.2 Thrombocytopenia Quinine-induced thrombocytopenia is an immune-mediated disorder. Severe cases of thrombocytopenia that are fatal or life threatening have been reported, including cases of HUS/TTP. Chronic renal impairment associated with the development of TTP has also been reported. Thrombocytopenia usually resolves within a week upon discontinuation of quinine. […]
Reported side effects
Most common adverse reactions are a cluster of symptoms called "cinchonism", which occurs to some degree in almost all patients taking quinine: headache, vasodilation and sweating, nausea, tinnitus, hearing impairment, vertigo or dizziness, blurred vision, disturbance in color perception, vomiting, diarrhea, abdominal pain, deafness, blindness, and disturbances in cardiac rhythm or conduction ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Lupin Pharmaceuticals, Inc. at 1-800-399-2561 or www.lupinpharmaceuticals.com. or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Overall Quinine can adversely affect almost every body system. The most common adverse events associated with quinine use are a cluster of symptoms called "cinchonism", which occurs to some degree in almost all patients taking quinine. Symptoms of mild cinchonism include headache, vasodilation and sweating, nausea, tinnitus, hearing impairment, vertigo or dizziness, blurred vision, and disturbance in color perception. More severe symptoms of cinchonism are vomiting, diarrhea, abdominal pain, deafness, blindness, and disturbances in cardiac rhythm or conduction. Most symptoms of cinchonism are reversible and resolve with discontinuation of quinine. The following ADVERSE REACTIONS have been reported with quinine sulfate. Because these reactions have been reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. General Fever, chills, sweating, flushing, asthenia, lupus-like syndrome, and hypersensitivity reactions. Hematologic Agranulocytosis, hypoprothrombinemia, thrombocytopenia, disseminated intravascular coagulation, hemolytic anemia; hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, idiopathic thrombocytopenic purpura, petechiae, ecchymosis, hemorrhage, coagulopathy, blackwater fever, leukopenia, neutropenia, pancytopenia, aplastic anemia, and lupus anticoagulant. Neuropsychiatric Headache, diplopia, confusion, altered mental status, seizures, coma, disorientation, tremors, restlessness, ataxia, acute dystonic reaction, aphasia, and suicide. […]
Interactions with other medicines
Interacting Drug Interaction Drugs known to prolong QT interval (e.g., Class IA and Class III antiarrhythmic agents). Quinine sulfate prolongs QT interval, ECG abnormalities including QT prolongation and Torsades de Pointes. Avoid concomitant use ( 5.3 ). Other antimalarials (e.g., halofantrine, mefloquine). ECG abnormalities including QT prolongation Avoid concomitant use ( 5.3 , 7.2 ). CYP3A4 inducers or inhibitors Alteration in plasma quinine concentration. Monitor for lack of efficacy or increased adverse events of quinine ( 7.1 ). CYP3A4 and CYP2D6 substrates Quinine is an inhibitor of CYP3A4 and CYP2D6. Monitor for lack of efficacy or increased adverse events of the co-administered drug ( 7.2 ). Digoxin Increased digoxin plasma concentration ( 5.8 , 7.1 ). See full prescribing information for a complete list of reported and potential interactions. 7.1 Effects of Drugs and Other Substances on Quinine Pharmacokinetics Quinine is a P-gp substrate and is primarily metabolized by CYP3A4. Other enzymes, including CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP2E1 may contribute to the metabolism of quinine [see CLINICAL PHARMACOLOGY ( 12.3 )] . Antacids Antacids containing aluminum and/or magnesium may delay or decrease absorption of quinine. Concomitant administration of these antacids with quinine sulfate should be avoided. Antiepileptics (AEDs) (Carbamazepine, Phenobarbital, and Phenytoin) Carbamazepine, phenobarbital, and phenytoin are CYP3A4 inducers and may decrease quinine plasma concentrations if used concurrently with quinine sulfate. Cholestyramine In 8 healthy subjects who received quinine sulfate 600 mg with or without 8 grams of cholestyramine resin, no significant difference in quinine pharmacokinetic parameters was seen. Cigarette Smoking (CYP1A2 Inducer) In healthy male heavy smokers, the mean quinine AUC following a single 600 mg dose was 44% lower, the mean C max was 18% lower, and the elimination half-life was shorter (7.5 hours versus 12 hours) than in their non-smoking counterparts. […]
Use in specific groups
Renal impairment: Reduce dose and dosing frequency for patients with severe chronic renal impairment ( 2.2 , 8.6 , 12.3 ). Hepatic impairment: Closely monitor for adverse events. Quinine should not be administered in patients with severe (Child-Pugh C) hepatic impairment ( 2.3 , 8.7 , 12.3 ). Pregnancy: Based on animal data may cause fetal harm. Use only if the potential benefit justifies the risk ( 8.1 ). Nursing Mothers: Exercise caution when administering to a nursing woman ( 8.3 ). 8.1 Pregnancy Pregnancy Category C There are extensive published data but few well-controlled studies of quinine sulfate in pregnant women. Published data on over 1,000 pregnancy exposures to quinine did not show an increase in teratogenic effects over the background rate in the general population; however, the majority of these exposures were not in the first trimester. In developmental and reproductive toxicity studies, central nervous system (CNS) and ear abnormalities and increased fetal deaths occurred in some species when pregnant animals received quinine at doses about 1 to 4 times the human clinical dose. Quinine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. P. falciparum malaria carries a higher risk of morbidity and mortality in pregnant women than in the general population. Pregnant women with P. falciparum malaria have an increased incidence of fetal loss (including spontaneous abortion and stillbirth), preterm labor and delivery, intrauterine growth retardation, low birth weight, and maternal death. Therefore, treatment of malaria in pregnancy is important. Hypoglycemia, due to increased pancreatic secretion of insulin, has been associated with quinine use, particularly in pregnant women. Quinine crosses the placenta with measurable blood concentrations in the fetus. In 8 women who delivered live infants 1 to 6 days after starting quinine therapy, umbilical cord plasma quinine concentrations were between 1.0 and 4.6 mg/L (mean 2.4 mg/L) and the mean (±SD) ratio of cord plasma to maternal plasma quinine concentrations was 0.32 ± 0.14. Quinine levels in the fetus may not be therapeutic. […]
If too much is taken
Quinine overdose can be associated with serious complications, including visual impairment, hypoglycemia, cardiac arrhythmias, and death. Visual impairment can range from blurred vision and defective color perception, to visual field constriction and permanent blindness. Cinchonism occurs in virtually all patients with quinine overdose. Symptoms range from headache, nausea, vomiting, abdominal pain, diarrhea, tinnitus, vertigo, hearing impairment, sweating, flushing, and blurred vision, to deafness, blindness, serious cardiac arrhythmias, hypotension, and circulatory collapse. Central nervous system toxicity (drowsiness, disturbances of consciousness, ataxia, convulsions, respiratory depression and coma) has also been reported with quinine overdose, as well as pulmonary edema and adult respiratory distress syndrome. Most toxic reactions are dose-related; however, some reactions may be idiosyncratic because of the variable sensitivity of patients to the toxic effects of quinine. A lethal dose of quinine has not been clearly defined, but fatalities have been reported after the ingestion of 2 to 8 grams in adults. Quinine, like quinidine, has Class I antiarrhythmic properties. The cardiotoxicity of quinine is due to its negative inotropic action, and to its effect on cardiac conduction, resulting in decreased rates of depolarization and conduction, and increased action potential and effective refractory period. ECG changes observed with quinine overdose include sinus tachycardia, PR prolongation, T wave inversion, bundle branch block, an increased QT interval, and a widening of the QRS complex. Quinine's alpha-blocking properties may result in hypotension and further exacerbate myocardial depression by decreasing coronary perfusion. Quinine overdose has been also associated with hypotension, cardiogenic shock, and circulatory collapse, ventricular arrhythmias, including ventricular tachycardia, ventricular fibrillation, idioventricular rhythm, and torsades de pointes, as well as bradycardia, and atrioventricular block [see WARNINGS AND PRECAUTIONS ( 5 ), CLINICAL PHARMACOLOGY ( 12.3 )] . […]
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This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 31 October 2025. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.